以Cu/ZnO/Al2O3觸媒進行甲醇蒸氣重組反應之研究

Optimization of Methanol Reformation Using Cu/ZnO/Al2O3 catalyst

鍾順章(Shun-Chang Chung)

指導教授 ： 吳和生

元智大學/工程學院/化學工程與材料科學學系/碩士(2005年)

摘要

摘要

本研究主要目的在於探討銅、鋅、鋁三者之間所組成之觸媒對於甲醇蒸氣重組反應的影響以及探討溫度、進料組成、進料流率、觸媒重量、載氣的選擇及含量對反應的影響。觸媒製作方法分別為草酸共沉澱法、多元醇含浸法和共沉澱法來製備。以草酸共沉澱法設計了27種Cu/ZnO/Al2O3比例觸媒，除了用傳統的方式逐一製備與分析外，另利用組合式化學的高效率分析法進行分析兩種方式做一比較，以氫氣的產生速率為標準，得到最適化的反應之銅觸媒。反應時則控制在觸媒0.1g至0.5g、進料組成H2O/CH3OH莫耳比0.4至2.0、反應溫度200℃至300℃及重量時空速率(WGSH, weight hourly space velocity)7.18至57.44(1/h)的條件下，載氣選擇為氦氣與空氣，而含量於15至50 SCCM。並將觸媒以ASAP(BET)、XRD、TPR、SEM等儀器進行觸媒特性的鑑定。
實驗結果於篩選觸媒方面，經由組合式化學高效率分析的方式可得到草酸共沉澱所合成的R10:5:5 Cu/ZnO/Al2O3重量比50:25:25觸媒擁有最高活性，不僅可得到與傳統方式逐一分析的方法有相同反應條件結果，分析的次數由27次降為9次，總分析時間大幅減少。不僅如此，再比較以R10:5:5為中心設計9種觸媒時，得到R15:15:5觸媒比例得到活性最佳。
若以R15:15:5為觸媒，配合最佳反應條件在溫度240℃，重量時空速率為14.36 1/h、H2O/CH3OH的比例1.2、觸媒重量0.3g、空氣含量為20SCCM時，可得到甲醇轉化率 97.6%，氫氣產生速率和濃度為0.671mole/h/g和58.89 vol%、一氧化碳產生速率和濃度為2.469 mmole/h.g和 0.2163 vol%，整體效果最佳，也能達重組器目標要求。
儀器的鑑定方面，從XRD 和TPR圖譜可發現製備方法草酸共沉澱法效果最好，而從BET觸媒表面積與銅觸媒活性面積得到R15:15:5觸媒表面積最大為71.10(m2/g)，銅觸媒活性面積最高為17.86(m2/g)，另外觸媒粒徑為14.59nm、分散度為8.252%、活性值(AA)184.5 mmole/hr和轉化數(TOF) 0.920*105 s-1。

關鍵詞:燃料電池、重組器、甲醇蒸氣重組反應、Cu/ZnO/Al2O3觸媒、化工動力學

關鍵字

燃料電池 ； 甲醇蒸氣重組反應 ； 銅鋅鋁觸媒

並列摘要

Abstract

The purpose of this research is to investigate the effect of composition include in Cu, Zn and Al and study temperature, feed composition, feed rate, catalyst weight, choice and content of carrier gas on methanol reformation. The catalyst were prepared by oxalic coprecipatation, coprecipatation and polyol method. Beside, there were 27 different Cu, Zn and Al ratio by oxalic coprecipatation to find the best cu/ZnO/Al2O3 catalyst determined by H2 production rate and compare between traditional and high analysis of combinatorial chemistry. The parameters for temperature is 200oC to 300oC, feed composition of H2O/CH3OH is 0.4 to 2.0, WHSV(weight hourly space velocity) is 7.18 to 57.44 1/h, catalyst weight is 0.1 to 0.5g, content of carrier gas are 15SCCM to50SCCM , carrier gas choice air and helium gas. Catalysts were characterized by ASAP (BET), XRD, TPR and SEM.
The results through traditional method or high analysis of combinatorial chemistry showed R10:5:5 have the best activity from initial 27 catalysts are same. Not only time of analysis decrease substantially, but times also can decrease from 27 times to 9 times. Further, based on Cu/ZnO/Al2O3 ratio closely to R10:5:5 to design other 9 catalysts, find R15:15:5 catalyst activity is highest.
R15:15:5 catalyst for temperature 240oC, WHSV 14.36 1/h, H2O/CH3OH ratio 1.2, catalyst weight 0.3g, air content 20SCCM on methanol reformation can get the optimum data that methanol conversion is 97.6%, H2 production rate and concentration are 0.671mole/h/g and 58.89 vol%, CO production rate and concentration are 2.469 mmole/h.g and 0.2163 vol%.
From XRD and TPR profile show Cu/ZnO/Al2O3 was prepared by oxalic coprecipatation method present the best method .From BET and Cu surface area can help to understand R15:15:5 (Cu/ZnO/Al2O3=42.85:42.85:14.3 ratio) have
bigget surface area 71.10(m2/g), highest Cu surface area 17.86(m2/g), particle size 14.59nm, dispersion 8.252%, activity(AA) 184.5mmole/hr and turnover frequency (TOF) 0.920*105 s-1。

Keyword: fuel cell、reformer、Steam reforming、Cu/ZnO/Al2O3 catalyst、chemical kineties.

並列關鍵字

fuel cell ； steam reforming ； Cu/ZnO/Al2O3

參考文獻

1. Bartel, D. P. and J. W. Szostak, Isolation of New Ribozymes from a Large Pool of Random Sequences. Science, 261, 1411-1418, (1993).

2. Bray, A.M., D.S. Chiefari , R.M. Valerio, and N.J. Maeji, Rapid Optimization of Organic Reactions on Solid Phase Using Multipin Approach: Synthesis of 4-Aminoproline Analogues by Reductive Amination, Tetrahedron Lett, 36, 5081-5084, (1995).

3. Bunin, B. A. and J. A. J. Ellman, A General and Expedient Method for the Solid Phase Synthesis of 1,4-Benzodiazepine Derivatives, J. Am. Chem. Soc, 114, 10997-10998, (1992).

4. Campbell, D. A., J. C. Bermak, T. S. Burkoth and D. V. Patel, A Transition State Analogue Inhibitor Combinatorial Library. J. Am. Chem. Soc, 117, 5381-5382, (1995).

5. Cubeiro, M.L., J.L.G. Fierro, Partial Oxidation of Methanol over Supported Palladium Catalysts, Appl. Catal A: Gen, 168, 307-322, (1998).